Sunan an Nasai
798
Sahih+2

It was narrated that Jabir said:"The Messenger of Allah (ﷺ) led us in Zuhr prayer and Abu Bakr was behind him. When the Messenger of Allah (ﷺ) said the Takbir, Abu Bakr said the Takbir so that the people could hear

SahihAbu Ghuddah
SahihAl-Albani